Investigating P0440 on Your 2024 Mercedes-Benz C-Class
Your 2024 Mercedes-Benz C-Class (W206) has triggered a P0440 code — an EVAP system malfunction. The C 300 uses a 2.0L turbo four-cylinder with EQ Boost mild-hybrid (255 hp), paired with a 9-speed automatic (9G-TRONIC) and available 4MATIC AWD. Mercedes uses a sophisticated EVAP system with an integrated leak detection pump. As a new vehicle under warranty, this should be simple. Let's gather the evidence.
Symptoms to Watch For
- Check engine light illuminated
- Faint gasoline odor
- Slight fuel economy decrease
- Fuel nozzle clicking off early
- Failed emissions inspection
Your C-Class drives perfectly normally. The turbo engine, 9G-TRONIC, and 4MATIC are completely unaffected.
Top Suspects: Ranked by Likelihood
- Fuel Filler Cap/Seal — Check the filler system first. Estimated repair: $0–$35.
- Leak Detection Pump (LDP) — Mercedes's EVAP diagnostic pump that pressurizes the system. Defect possible on new vehicles. Estimated repair: $160–$380 (warranty-covered).
- Purge Valve (Regeneration Valve) — Mercedes term for the purge solenoid controlling vapor flow. Estimated repair: $120–$290 (warranty-covered).
- Shut-Off Valve — Controls EVAP system venting near the charcoal canister. Estimated repair: $130–$310 (warranty-covered).
- EVAP Line or Connection — Loose factory fitting. Estimated repair: $0–$130 (warranty).
Diagnostic Steps
- Check fuel filler, clear code, drive 50+ miles
- Schedule Mercedes dealer appointment — warranty applies
- Dealer will use Mercedes XENTRY/DAS diagnostics for EVAP testing
- Check for TSBs on the W206 C-Class
Repair Cost Breakdown
- Fuel filler: $0–$35
- Leak detection pump: $160–$380 (warranty)
- Purge valve: $120–$290 (warranty)
- Shut-off valve: $130–$310 (warranty)
- EVAP connection: $0–$130 (warranty)
Warranty: Your 2024 C-Class is covered by Mercedes-Benz's 4-year/50,000-mile basic warranty. All EVAP repairs are free.
Can I Drive With P0440?
Yes. P0440 is emissions-only with no performance or safety impact.
DIY or Dealer?
Dealer — Mercedes's 4-year warranty covers the repair at no cost.